Metal foil for heating and cooling foods and method of making same

Abstract

An improved metal foil composite sheet and method of fabricating the same for heating and/or cooling food products. Metal foil is coated on one surface with a heat stable, thermoplastic, epoxy and on its second surface with a heat resistant, dielectric, thermosetting base coat and a top coat of a heat resistant, heat absorptive, thermosetting material. The top coat may be applied in zones of distinct thicknesses simultaneously. Such application provides for legible printing, while preserving the desired heat absorptive properties on the entire foil pouch stock including both the printed and unprinted regions. A completed foil pouch composed of the foil composite sheet permits uniform heating and/or cooling of foods over an extended range of temperatures and times while resisting undesired deterioration.

I claim: 
     
       1. A method of fabricating a composite sheet comprising: providing a metal foil material,   applying a layer of heat stable, thermoplastic material on a first surface of said foil material,   applying a layer of a heat resistant, dielectric material on a second surface of said foil material,   applying a layer of a heat resistant, heat absorptive material in at least two distinct layer thicknesses over said heat resistant, dielectric layer or portions thereof so as to provide a layer visually distinguishable from the heat resistant, dielectric layer,   applying said heat resistant, heat absorptive material on a first portion of said dielectric material which is to be disposed within the lower one-half of a foil pouch formed from said foil stock and covering at least 10% of said dielectric material with a coating weight of about 1.50 to 4.00 pounds per ream, and   applying said heat resistant, heat absorptive material on at least a second portion of said dielectric layer at about 15% to 70% less than the coating weight applied to said first portion.   
     
     
       2. The method of claim 1 comprising providing said layer of dielectric material by means of a material which is heat absorptive. 
     
     
       3. The method of claim 1 comprising applying said layer of heat resistant, heat absorptive material as a coating. 
     
     
       4. The method of claim 3 comprising applying said heat resistant, heat absorptive coating in at least two distinct layer thicknesses simultaneously. 
     
     
       5. The method of claim 4 comprising applying said heat resistant, heat absorptive coating over at least 60% of said dielectric material. 
     
     
       6. The method of claim 1 comprising: providing a minimum of about 5% by weight of a heat receptive additive in said heat resistant, heat absorptive material applied to said layer of heat resistant, dielectric material, and   said heat receptive additive being characterized by a minimum emissivity of about 80%.   
     
     
       7. The method of claim 6 wherein said heat receptive additive is carbon black.